1. Field of the Invention
The invention relates generally to a method of manufacturing copper wiring in a semiconductor device. More particularly, the invention relates to a method of manufacturing copper wiring in a semiconductor device, which has a good coverage characteristic and can prevent generation of voids, etc., and thus is capable of improving reliability of a device, by which a diffusion prevention film is formed on a damascene pattern, a first copper film is formed by a PVD method, a second copper film is formed by a spin-on coating method, and a third copper film is formed by PVD or an electrochemical deposition method.
2. Description of the Prior Art
A prior art method of manufacturing a copper wiring in a conventional semiconductor device is explained below with reference to FIG. 1.
An insulating film 12 is formed on a semiconductor substrate 11 in which a predetermined structure is formed. Then, a predetermined region of the insulating film 12 is patterned by a dual damascene process to form a trench through which the predetermined region of the semiconductor substrate is exposed. Next, a diffusion prevention film 13 is formed on the entire structure, including the trench. Thereafter, a seed layer 14 is formed by means of a PVD method. Then, a copper film 15 is formed by an electochemical deposition method so that the trench can be completely filled. Next, after the copper film 15 is cured by an annealing process, it is polished by a CMP process to form copper wiring.
If the copper wiring is formed by the above process, the coverage characteristics of the diffusion prevention film and the seed layer formed by CVD method are degraded as the device is highly integrated. Therefore, the diffusion prevention does not function properly or copper atoms 16 enter the insulating film through the diffusion prevention film. Due to this, when the copper layer is formed by an electrochemical deposition method, a void 17 is created which adversely affects reliability of the wiring.
Also, the copper layer is formed by an electrochemical deposition method after the diffusion prevention film and the seed layer are formed, and breakage of vacuum is caused to form a copper oxide film 18 on the seed layer. Therefore, even after the copper layer is deposited by an electrochemical deposition method, the copper oxide film 18 exists within the wiring, thus adversely affecting reliability of the device. In addition, as the copper layer formed by electrochemical deposition is formed using additives, many impurities exist in the deposited copper layer to adversely affect the copper metal layer.
It is expected that as the device is highly integrated, the conventional method becomes difficult to use. Therefore, there is a need for a copper wiring method that has better coverage and results in fewer impurities.
A method of manufacturing a copper wiring in a semiconductor device includes the steps of forming an insulating film on a semiconductor substrate in which a given structure such as an underlying conductive film is formed, and then sputtering the insulating film by a dual damascene process to form a trench through which the underlying conductive layer of the semiconductor substrate is exposed; removing a metal oxide film remaining on the exposed underlying conductive layer to form a diffusion prevention film; after forming a first copper film on the entire structure, forming a second copper film and performing an annealing process until a desired thickness is formed, thus forming a copper oxide film on the second copper film; removing the copper oxide film to form a third copper film on the entire structure; and polishing the third, second and first copper films, and the diffusion prevention film by CMP process to form a copper wiring.